This invention relates to a method of forming high-temperature resistance polymers by a 2-stage curing process, particularly for use in the field of adhesives, sealants, thread-locking compositions, gaskets and the like.
U.S. Pat. No. 4,543,397 Woods et al, describes polyfunctional cationically polymerizable styryloxy compounds of the formula I or II ##STR1## where R.sup.1 and R.sup.2 are H, or one of R.sup.1 and R.sup.2 is H and the other is methyl; R.sup.3 and R.sup.4 are H, lower alkyl or alkoxy if R.sup.2 is not methyl; R.sup.5 is a divalent hydrocarbon radical; G is a multivalent organic or inorganic radical free of amine, aliphatic hydroxyl, aliphatic thiol or other groups which interfere with cationic polymerisation; and n is an integer of two or more.
The polyfunctional telechelic styryloxy monomers of the kind described in U.S. Pat. No. 4,543397 are generally of high molecular weight. Even so, example 10 of that Patent describes the preparation of 4-allyloxystyrene of the formula III ##STR2##
This compound is cationically active but it forms linear polymers which are purple/blue in colour and only 10% insoluble in organic solvents i.e. little if any crosslinking has occurred. That which may occur likely results from radical initiation of the allyl group since radicals may also be produced from the photocationic initiator.
Our U.S. patent application Ser. No. 07/625,725 now U.S. Pat. No. 5,084,490 entitled "Styryloxy Compounds and Polymers Thereof" of even date herewith describes styryloxy compounds of the formula IV ##STR3## wherein R.sup.1 and R.sup.2 are H, or one of R.sup.1 and R.sup.2 is H and the other is methyl; R.sup.7 and R.sup.8 (which may be the same or different) are H, C.sub.1 -C.sub.5 alkyl or C.sub.1 -C.sub.5 alkenyl; or one of R.sup.7 and R.sup.8 may be --OR.sup.6 or C.sub.1 -C.sub.5 alkoxy or C.sub.1 -C.sub.5 alkenyloxy if R.sup.2 is not methyl; and R.sup.6 is selected from the group consisting of: ##STR4## where R.sup.10 is C.sub.1 -C.sub.5 alkyl; and R.sup.11, R.sup.12 and R.sup.13, which may be the same or different, are H or C.sub.1 -C.sub.5 alkyl.
The most preferred compounds are of the formula V ##STR5## wherein R.sup.9 is selected from the group consisting of: ##STR6##
The compounds of said Patent Application are monofunctional with respect to the styryl group but are difunctional because of the other cationically active substituent --OR.sup.6 or --OR.sup.9. They are compatible with photoinitiators and can be photocured to give highly transparent polymeric films with good mechanical properties after short irradiation times e.g. 10 seconds or less. The Patent Application also describes mixed styryloxy compositions comprising a compound of the formula IV and allyloxystyrene.